Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel the sweet potato and cut it into 1/2-inch cubes, then toss them in a bowl with the olive oil, 0.25 tsp sea salt, and 0.125 tsp black pepper.
Spread the sweet potatoes onto the prepared baking sheet and roast for 15 minutes.
While the potatoes roast, mince the garlic clove and zest half of the lemon.
In a small bowl, combine the ghee, minced garlic, lemon zest, dried oregano, and the remaining salt and pepper to create a herb rub.
Pat the chicken breast dry and coat it thoroughly with the herb rub on all sides.
Move the sweet potatoes to one side of the baking sheet and place the chicken breast on the other side, topping the chicken with thin slices of the lemon.
Return the pan to the oven and roast for an additional 18 to 22 minutes, or until the chicken reaches an internal temperature of 165°F.
While the chicken finishes, steam the broccoli florets in a steamer basket over boiling water for 4 to 5 minutes until tender-crisp.
Allow the chicken to rest for 5 minutes before slicing and serving alongside the roasted sweet potatoes and steamed broccoli.